musclar system

Question 1

what are the 3 muscle types

Answer 1

skeletal
cardiac
smooth

Question 2

what are cardiac muscles

Answer 2

e.g. myocardium
function: pumps blood around the body and delivers 02 to cells and removing waste
-involuntary: heart
-initiated its own impulse at the SAN (myogenic)
-rate/force of contraction is controlled by the sympathetic/parasympathetic or vagus nerve

Question 3

what are smooth muscles

Answer 3

e.g. arteries, digestive system
function: contacts to direct blood flow (arteries) contacts to push flood through the digestive tract
-involuntary: medulla oblongata
-sends impulses to control blood flow
-flood moves along the digestive tract via peristalsis (a squeezing action)

Question 4

what are skeletal muscles

Answer 4

e.g. gluteus maximus
fuction: movement, maintains posture, produces heat through shivering, stores glycogen
-voluntary: medulla oblongata
- sends electrical impulses (action potential)
-contacts 3 ways:
.concentric
.isometric
.eccentric

Question 5

what is the epimysium

Answer 5

surrounds the whole of the skeletal muscle

Question 6

what is the perimysium

Answer 6

surrounds each fascicle

Question 7

what is the fascicle

Answer 7

a bundle of muscle fibres

Question 8

what is the endomysium

Answer 8

surrounds each muscle fibre

Question 9

what is the sarcolemma

Answer 9

membrane between the endomysuim and muscle fibres conducts action potential

Question 10

what is the myofibril

Answer 10

smallest unit which is broken down into sarcomere by z-lines

Question 11

rank the skeletal muscles largest to smallest

Answer 11

largest
epimysuim
perimysium
fascicle
endomysium
sarcolemma
muscle fibres
myofibril

Question 12

what are type 1 muscle fibres (slow twitch fibres)

Answer 12

1)contacts slowing and with less force
2)they are slow to fatigue and suited to long duration aerobic activities
3) they have a rich blood supply and contain many mitochondria to sustain aerobic metabolism
4) they have a high capacity for aerobic respiration

Question 13

what are type 11a muscle fibres (fast twitch/ fast oxidative fibres)

Answer 13

1) fast contracting able to produce a greater range force and resistant to fatigue
2) they are less reliant on oxygen for energy supplied by the blood and fatigue faster than slow twitch fibres

Question 14

what is type 11x muscle fibres (fast-twitch/ fast glycolytic fibres)

Answer 14

1) contracts rapidly and have the capacity to produce large amounts of force but fatigue faster so are suited to anaerobic activity
2) they depend almost entirely on anaerobic respiration and are recruited for high intensity short duration activity

Question 15

what is a neuromuscular junction

Answer 15

is where the end of the nerve synapses (meets) a muscle fibre. when the nerve carries on electrical singal it passes this to the muscle to make it contact

Question 16

explain the stages of a neuromuscular junction

Answer 16

1) electrical impulses starts in the brain travels down the spinal cord along the motor neurone and arrives in the axon terminal. Here the electrical impulses is now known as action potential.
2) when an action potential arrives at the axon terminal it opens voltages gated calcium ions channel. Allowing Ca+ ions into the axon terminal
3) Ca+ ions attach to vesicles in the axon terminal which contains the neurotransmitters acetylcholine. Once bonded the vesicles moves to the pre-synaptic membrane and releases its acetylcholine into the synaptic cleft
4) acetylcholine in the synaptic cleft diffuses across to the chemical gated Na+ ion channel and binds to receptors on the channel to open it and allow Na+ ions into the muscles fibres across the past synaptic membrane
5) after entering the muscle fibres sodium ions generate an action potential this travels across the sarcolemma down the t-tubule
6) the action potential moves from the t-tubule into the terminal cisternae either side opening the Ca+ ion channel. Ca+ ions now move through the channel into the muscle fibre. If the action potential remains stored calcium will be released into the terminal cisternae

Question 17

what’s the sliding filament theory

Answer 17

explains how the sarcomere operates and therefore a muscle contracts when stimulated by an action potential

Question 18

explain the sliding filament theory

Answer 18

1)Ca+ ions from terminal cisternae bind to troponin which pulls on the tropomyosin to expose the binding sites on actin filament
2) the myosin heads on myosin filament attach to the binding sites on actin filament forming a cross bridge when this happens the phosphate is released
3) a power matron so then performed when the myosin heads lather their angle towards the middle of the sarcomere pulling the actin filament over the myosin filament. When this happens the ADP comes away from the myosin head
4) the cross bridge has been broke by ATP and it returns the myosin back to its original position. During the process the ATP breaks down into ADP and Pi
5) when the muscle is no longer stimulated by an action potential the Ca+ ions are reabsorbed into the terminal cisternae. So there is nothing to bind to troponin and moves the tropomyosin from the actin binding sites. Muscle contraction stops